Switching device



June 2, 1959 H. J. LINGAL 2,889,434

SWITCHING DEVICE Original Filed Oct. 26, 1951 I 5 sheets-sheet 1 INVENTOR Hurry J.Lingol. B

Y WM i? M ATTORNEY June 2, 1959 H. J. LINGAL SWITCHING DEVICE Original Filed Oct. 26, 1951 3 Sheets-Sheet 2 INVENTOR Hor J.L' I. BY ry lngo m K M ATTORNEY United States Patent SWITCHING DEVICE Harry J. Ling'al, Pittsburgh, Pa., assignor to Westing= house Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Original application October 26, 1951, Serial No. 253,321, now Patent No. 2,769,063, dated October 30, 1956. Divided and this application April 9, 1956, Serial No. 576,875

15 Claims. (Cl. 200-'-,-148) This invention relates to circuit interrupting devices in general, and more particularly, to disconnecting switches with particular relation to disconnecting switches that are adapted to be opened and closed in an arc-extinguishing gas having high dielectric strength.

This application is a division of applicants parent application, filed October 26, 1951, Serial No. 253,321, issued October 30, 1956 as United States Patent 2,769,063, and assigned to the assignee of the instant application.

In many instances it is desirable to open a high voltage disconnecting switch while normal load current is fiowing in the circuit in which it is connected. For example, in many installations, high voltage transformers are constantly connected to the high voltage line and infrequently require servicing. It is then necessary to disconnect such a high voltage transformer from the high voltage circuit, and during such disconnecting operation it is necessary to interrupt the magnetizing current flowing from the high voltage line into the high voltage transformer.

If this magnetizing cuirent were drawn between the blade-shaped contact and the stationary jaw contact of a conventional disconnecting switch, the contact surfaces would become pitted or eroded so that following only a few such operations the contact surfaces would not be suitable for carrying the full load current. Thus the switch members would become binned or fused because of the heat of the arc depending upon the amount of current in the circuit at the particular instant that the switch is opened.

There is also the possibility, under more severe circuit conditions, that a long are may be sustained and establish itself between the switch and an adjacent circuit or ground when the attempt is made to interrupt the load current by a conventional disconnecting switch. It is a general purpose of my invention to provide an improved load-break disconnecting switch which will interrupt the load current interiorly within an arc interrupting structure and not exteriorly thereof at the open switch contacts.

A further object of my invention is to provide an improved and highly eflicient load-break disconnecting switch in which the contact structureof the arc-extinguishing device is opened and closed by snap action.

Still a further object of my invention is to provide an improved operating mechanism for the contacts of a switch for operating at high voltages.

Yet another object is to provide a switch in which the circuit is made and broken Within an entirely enclosed device, and, during the closing operation, the circuit is made between the contacts of the device in an arcextinguishing gas.

Still a further object of my invention is to provide a load-break disconnecting switch particularly suitable 2,889,434 Patented June 2, 1959 for interrupting high voltage circuits, in which use is made of the length of the arc-interrupting device for holding the voltage during high voltage operation.

A further object is to provide an improved snap-acting over-center spring mechanism for a switch.

A further object is to provide an improved enclosed switch particularly suitable for enclosing an arcextinguishing gas in a sealed state, and to provide improved sealing structure to prevent escape of the gas.

Another object is to provide an improved interrupting device utilizing a pressurized interrupting chamber for high-dielectric strength condition of theenclosed pres surized gas, in which a piston structure movable with the movable contact is employed to obtain an effective blast of arc-extinguishing gas by diiferential pressure across the piston structure.

Still a further object is to provide an improved and highly efficient disconnecting switch which may be economically manufactured, simple to service and which will give a long trouble-free interrupting life.

Further objects of my invention will readily become apparent upon reading the following specification, taken in conjunction with the drawings, in which:

Figure 1 is a plan view of my improvedload-break disconnecting switch, the contact structure being illustrated in the closed circuit osition;

Fig. 2 is a side elevational view of the load-break disconnecting switch pictured-in Fig.- l, the contact structure being shown in the closed circuit position, the figure also showing the fully open circuit position in chain line's; i

Fig. 3 is a vertical sectional view drawn to an enlarged scale, of the arc-interrupting device of the load-break disconnecting switch illustrated in Figs. 1 and 2, the contact structure being shown in the closed circuit position;

Fig. 4 is a sectional plan view taken: substantially along the line IV'IV of Fig. 3, the contact structure being shown in the closed circuit position;

Fig. 5 illustrates a modified type of load-break dis connecting switch, the contact structure being illustrated in the closed circuit position; i

Fig. 6 is a view similar to that of Fig. 5, showing the modified type of load-break disconnecting switch in the open circuit position; and

Fig. 7 is a fragmentary vertical sectional view through a portion of a modified type of load-break disconnecting switch, similar to that set out in Figs. 5' and 6, the contact structure being shown in the closed circuit position.

Referring to the drawings, and more particularly to Figs. 1 and 2 thereof, it will be observedthat there are provided three stacks of insulator columns 1, 2 and 3 supported upon a suitable base structure 10 (Fig. l). The insulator stacks 1, 2 and 3 may extend a consider able distance upwardly from the base structure 10 when the switch is utilized on a high voltage circuit. Pref+ erably, the insulator columns 1 and 3 are fixed, whereas the insulator column 2 is adapted for rotating movement by a crank arm 2a, to eifect thereby operation of the mechanism for the load-break disconnecting switch, generally designated by the reference numeral 4, and which is supported at the upper ends of the insulator columns 1-3.

Supported at the top of stationary insulator column 1 is an arc-extinguishing interrupting device, generally designated by the reference numeral 6. Also supported at the top of the stationary insulator column 1 is a relatively,

stationary jaw switch contact, designated by the reference numeral 7, and which cooperates with the contacting end 8 of a disconnecting switch blade 9, which is secured to a cam housing 11, the latter being pivotally supported by trunnions 12. The trunnions 12 extend inwardly from a housing casting 13, which has an extension 14 including a line terminal plate 15.

The other line terminal plate of the load-break disconnecting switch 4 is designated by the reference numeral 16, and constitutes an extension of a support casting 17 fixedly supported at the top of insulator column 1. Thus the circuit passes through the disconnecting switch 4 from line terminal plate 16, support casting 17, stationary jaw contact 7, movable contact 8 of switch blade 9, through the switch blade 9 to conducting cam housing 11, and thence through trunnions 12 and casting 13 to line terminal plate 15.

As is well known to those skilled in the art, suitable means are provided to efiect upward swinging opening motion of the switch blade 9 about its pivot 12 to the open circuit position, as indicated by the chain lines 18 of Fig. 2. In this position a long isolating gap in air is provided between the switch contacts at opposite potential.

Referring more particularly to Fig. 3, which more clearly shows the internal construction of the arc-extinguishing interrupting device 6, it will be observed that this device includes a weatherproof porcelain casing 19, supported vertically in an upstanding position upon the support casting 17. The engagement between the lower end of the porcelain casing 19 and the support casting 17 may be elfected by a suitable cement 20, interposed between a lower corrugated portion 21 of the ceramic casing 19 and interiorly disposed corrugations 22 provided within an upstanding flange portion 23, the latter being secured by suitable means, not shown, to the casting 17.

At the upper end 24 of the weatherproof casing 19 is fixedly secured by cement 25, a mounting flange 26, the latter being secured by bolts 27 to a mechanism housing casting 28, the latter having a cover plate 29. Preferably, the cover plate 29 is secured by bolts 30 to the housing 28, a suitable gasket 31 being interposed therebetween to efiect a gas-tight connection.

Disposed interiorly within the weatherproof casing 19 is an arc-extinguishing unit, generally designated by the reference character 32, and including an upstanding insulating cylinder 33 within which reciprocates a movable contact rod 34 having a piston 35 secured thereto and making a relatively close fit with the interior wall of the insulating cylinder 33.

A movable contact 36, secured to the lower end of the movable contact rod 34, makes abutting engagement with a relatively stationary contact 37, the latter being resiliently supported by means of a contact compression spring 38. The contact compression spring 38 is disposed within a stationary contact support tube 39, which has a stationary pin 40 extending therethrough near its upper end. The pin 40 extends through an elongated slot 41 provided near the lower end of the stationary contact 37, so that during the closing stroke the stationary contact 37 may move resiliently downwardly with respect to the support tube 39 and the pin 40, compressing the spring 38 for the requisite contact pressure between the stationary and movable contacts 37, 36, respectively. A flexible conducting strap 39a electrically interconnects the stationary contact 37 with a conducting base 42, hereinafter described.

I mount the support tube 39 upon a conducting base 42, which is secured, as by threaded engagement, to a conducting closure plate 43, the latter being secured by means not shown to the flange portion 23 of the support casting 17. Disposed at the lower end of the conducting base 42 is a pressure gauge 44, which faces downwardly and may be visually observed from the base structure 10 for the load-break disconnecting switch 4. Thus a station attendant may look upwardlyfrom below the base structure 10 for the load-break disconnecting switch 4, and observe the pressure registered upon the dial of the pressure gauge 44. This pressure gauge 44 indicates the gas pressure which is present within the interior 45 of the casing 19, the latter, as previously mentioned, having a gas-tight construction.

I prefer to fill the casing 19, by way of the gauge attachment 44, with a suitable arc-extinguishing gas, such as sulfur hexafluoride, or some other suitable arc-extinguishing gas which has preferably better interrupting properties than ordinary air. The remarkable interrupting properties of sulfur hexafiuoride, and the theory pertaim ing to its interrupting performance, is set out and claimed in United States patent application filed July 19, 1951, Serial No. 237,502, now United States Patent 2,757,261, issued July 31, 1956, to Harry I. Lingal, Thomas E. Browne, Jr. and Albert P. Strom and assigned to the assignee of the instant application.

The movable contact rod 34 is moved upwardly within the insulating cylinder 33 by a snap-acting over-center toggle mechanism, generally designated by the reference numeral 46, and enclosed interiorly within the mechanism housing casting 28. This mechanism 46 includes a U- shaped bracket 47 secured by a pair of bolts 48 to a support portion 49 of the casting 28. The U-shaped bracket 47 has apertures provided in its upstanding legs 58 through which extends a pivot pin 51. Supported on the pivot pin 51 is a U-shaped link 52, the legs 53 of which have apertures provided at their upper ends. A pivot pin 54 extends through the apertures provided in the upper ends of the legs 53, and supports a U-shaped arm 55, the configuration of which is more clearly shown in Fig. 4. One leg 56 of the arm 55 is longer than the other leg 57, and is pivotally connected at its outer extremity, as at 58, to the upper end of the movable contact rod 34.

At the extremity of the other leg 57 of the arm 55 is an aperture, through which passes a pivot pin 59, the latter also extending through an aperture 60 provided intermediate the ends of the longer leg 56 of the arm 55.

The pin 59 supports a U-shaped toggle link 61 at the left-hand end thereof, as viewed in Fig. 3. The righthand ends of the legs 62, 63 of the toggle link 61 are slotted, as at 64. The slot 64 of the upper leg 62 of the toggle link 61, as viewed in Fig. 4, is mounted upon a trunnion 65, the latter being journalled in a bearing por- The slot 64 of the lower leg 63 of the toggle link 61, as viewed in Fig. 4, accommodates a crankshaft 68, more clearly shown in Fig. 4. The trunnion 65 also supports one leg 69 of a toggle link, generally designated by the reference numeral 70, the lower leg 71 of which has a collar 72 secured thereto, as by brazing. which is fixedly secured to the inner end of the crankshaft 68 by a key pin 73, as shown in Fig. 4.

Thus, rotation of the crankshaft 68 will etiect rotation of toggle link secured thereto, efiecting thereby opening and closing of the contact structure associated with the arc-extinguishing unit 32.

Preferably a tension spring 75 is interposed between the pin 59 and a pin 76 extending through apertures 77 provided in the legs 69, 71 of the toggle link 70. Spacers 78 are employed encircling the pins 59, 76, to maintain the tension spring 75 at a relatively fixed location. A stop 80 is provided, constituting an upwardly projecting boss of the casting 28, which arrests clockwise rotation of the toggle link 70, as shown in Fig. 3. A second stop 81, which is preferably made adjustable, is provided extending downwardly from the cover plate 29 to strike the toggle link 61 during the opening operation, to arrest the same, as shown by the chain lines 82 in Fig. 3. An adjustable stop 70a is provided to arrest counterclockwise rotation of toggle link 70 during the opening operation.

tion 66 provided in the side wall 67 of the housing casting The tension spring 75, as more clearly shown in Fig. 3, tends to effect collapse of the toggle link 70 and toggle link 61 in the open and closed circuit positions of the interrupter, as indicated in Fig. 3.

It will be noted that the crankshaft 68 extends through a bearing portion 83 provided in the side wall 84 of the casting 28, and also extends through a laterally jutting gas-tight housing 85, more clearly shown in Fig. 4. The gas-tight housing 85 comprises, as shown, a cylindrical portion which may be welded, as at 86, to the side wall 84 of the casting 28. The housing 85 also includes an apertured closure plate 87 secured to the housing and through which the crankshaft 68 extends, to be externally rotated by a triangularly-shaped operating crank, generally designated by the reference numeral 83.

As more clearly shown in Figs. 1, 2 and 4, the operating crank 88 includes a plate 89 having a portion 90 removed therefrom to make it of lighter construction. Also the plate 89 has two triggers or engaging shafts 91, 92, as more clearly shown in Fig. 2, which are engaged during the opening and closing operations by the contact end of the disconnecting switch blade 9.

Consequently, during the opening operation of the loadbreak disconnecting switch 4, the contact end 8 of the switch blade 9 engages the engaging shaft 91 of operating crank 88 to effect thereby rotation of crankshaft 68 to effect an extension of the tension spring 75 when the toggle link 70 is moved counterclockwise, as viewed in Fig. 3. When the pins 59, 76 and crankshaft 68 are on a straight line the mechanism 46 is in its fully extended condition. Further counterclockwise rotation of crankshaft 68 will effect collapse of the toggle link 7?; and toggle link 61, as indicated by the chain lines 82 of Fig. 3. The result will be a snap-opening motion of the movable contact 36 upwardly away from the relatively stationary contact 37 and a compressing of the gas within the region 93 on the upper side of the piston 35. The piston 35 will consequently compress the gas within the region 93- and compel it to flow through the nozzle 94 of an orifice member 95, through which the load current are is drawn. The flow of the compressed gas through the orifice member 95 will effect extinction of the are drawn between contacts 36, 37, the hot gases passing out one or more vents 79 through the base 42.

After operating crank 38 has been snapped to its upper position, as viewed by the chain lines 96 of Fig. 2, the location of the engaging shaft 91 in this position is clear of the line of movement of switch blade 9; and switch blade 9 continues to move to the fully open circuit position of the switch, as indicated by the chain lines 18 of Fig. 2.

During the closing operation the contact end 8 of switch blade 9, in moving in a counterclockwise direction about pivots 12, as viewed in Fig. 2, will strike engaging shaft 92, which at this time is in the line of movement of switch blade 9.

The switch blade 9 will hence strike engaging shaft 92 to forcibly eir'ect clockwise rotation of operating crank 88 and hence also of crankshaft 68, to thereby efiect clockwise rotation of toggle link 70 from its chain line position 97, as viewed in Fig. 3, to its full line position as viewed in Fig. 3. As in the opening operation, so in the closing operation the tension spring 75 is first extended and then efiects collapse of .the toggle link 61 and the toggle link "it? to effect a snap-closing motion of the contacts 36, 37.

To enable the electrical circuit to pass through the arc-extinguishing interrupting device 6 following separation of the contact end 8 of the switch blade 9 from the stationary jaw contact 7, I provide an auxiliary conducting contact arm 99 pivotally mounted about a pivot 101), which is in registry with the pivot axis 12. As more clearly shown in Fig. 2, the free end 1131 of the auxiliary contact arm 99 makes contacting engagement with a stationary U-shaped contact or terminal 102 fixedly secured by bolts 103 to the cover plate 29 of the housing 28. Means are provided to bias the auxiliary contact arm 99 toward the switch blade 9, in this instance including a spring tube 104 within which is a compression spring 107. The compression spring 107 is seated at its lower end, as viewed in Fig. 2, against a cap 107a of the spring tube 104. The upper end of the compression spring 107 is seated against an apertured spring plate 107b secured to the free end of a spring rod 105. The lower end of the spring rod 105 is pivotally mounted at a movable pivot 106 of the cam housing 11, more clearly shown in Fig. 1 of the drawings. Fundamentally, the spring tube 104 acts somewhat as a tension spring to bias the two arms 9, 99 together. Also the switch blade 9 has a laterally extending hook 5 which engages the arm 99 during the opening operation to carry the latter therewith to the fully open position.

From the foregoing description, it will be readily ap parent now the load-break disconnecting switch 4 operates. However, to recapitulate, in the closed circuit position of the device the electrical circuit therethrough in cludes line terminal plate 16, support casting 17, stationary jaw contact 7, movable contact 8 of switch blade 9, through the switch blade 9 to conducting cam housing 11, and thence through trunnions 12 and casting 13 to line terminal plate 15.

A separate circuit in parallel to that mentioned is available in the closed circuit position of the device. It includes line terminal plate 16, support casting 17, conducting flange portion 23, plate 43, conducting base 42, flexible conductor 39a, stationary contact 37, movable contact 36, movable contact rod 34, flexible conductor 74 to the mechanism housing 28, through terminal 192 and auxiliary contact arm 99 to earn housing 11, and thence through trunnions 12 and casting 13 to line terminal plate 15. Since the second parallel circuit through the interrupting device 6 contains more resistance than the main circuit directly through the switch blade 9, practically all the current flows through the first-mentioned circuit including switch blade 9.

To open the switch 4 from the closed circuit position thereof suitable means, not shown, effects counterclockwise rotation of the crank arm 2a and hence insulator column 2, as viewed in Fig. 1. This rotating movement of insulator column 2 actuates a cam interiorly within cam housing 11 in a manner more fully disclosed in United States Patent 2,436,296, issued February 17, 1948, to Howard W. Graybill and Paul Olsson and assigned to the assignee of the instant application. The first portion of the cam motion efiects a twisting, or axial rotation of the switch blade 9 so that any ice formed between the stationary and movable contacts 7, 8 may be broken free.

Following such initial twisting motion of the switch blade 9, the cam motion taking place within the cam housing 11, as set out in the aforesaid patent, causes clockwise rotative movement of the switch blade 9 about the pivot 12, as viewed in Fig. 2. When the contacting portion 8 of switch blade 9 separates from stationary jaw contact 7 the electrical circuit is then forced to take the second parallel path previously mentioned through the arc-extinguishing interrupting device 6. This circuit includes line terminal plate 16, support casting 17, conducting flange portion 23, plate 43, conducting base 42, flexible conductor 39a, stationary contact 37, movable contact 36, movable contact rod 34, flexible conductor 74 to the mechanism housing 28, through terminal 102 and auxiliary contact arm 99 to cam housing 11, and thence through trunnions 12 and casting 13 to line terminal plate 15.

Continued clockwise rotation of switch blade 9 brings the free end 8 thereof into engagement with engaging shaft 91 to eifect thereby counterclockwise rotative motion of operating crank 88 and: hence opening motion of the mechanism 46, as previously described. This will effect opening of the contact structure 36, 37 and extinction of the are drawn therebetween through the orifice member 95 by a flow of gas, which is compressed above the piston 35 within the region 93.

When this are is extinguished, the electrical circuit through the load-break disconnecting switch 4 is interrupted. Continued clockwise movement of switch blade 9 causes hook 5 to strike arm 99 and brings the blade 9 and arm 99 to the open circuit position, as shown by the chain lines 18 of Fig. 2. It is to be noted that the spring tube 104, being equivalent to a tension spring, maintains the auxiliary contact arm 99 in contact with contact 102 until struck by hook 5 of blade 9.

To effect a closing of the switch 4, it is merely necessary to cause, by a suitable mechanism, clockwise rotative movement of crank arm 2a and hence the insulator column 2, as viewed in Fig. 1. This will cause through the cam motion taking place within the cam housing 11, first counterclockwise rotative movement of the switch blade 9, as viewed in Fig. 2, the auxiliary contact arm 99 being moved therewith by functioning of the spring tube 104 and gravity.

Near the end of the closing stroke the contact arm 99 strikes the stationary contact 102. Further movement causes a separation to occur between the switch blade 9 and the contact arm 99, with the contact end 8 of switch blade 9 striking engaging shaft 92 of operating crank 88, which at this time is in the path of movement of switch blade 9. The contact 8 will strike engaging shaft 92 and will effect thereby clockwise rotation of operating crank 88 to effect closing movement of the mechanism 46 disposed interiorly within mechanism housing casting 28. This will effect snap-action closing engagement between the contacts 36, 37 to bring about closing of the electrical circuit through the load-break disconnecting switch 4 prior to the closing of the contacts 7, 8.

Finally, the contact 8 of switch blade 9 engages jaw contact 7, and the final movement of the cam mechanism within cam housing 11 is to effect an axial twisting motion of switch blade 9 to bring about firm contacting engagement between contacts 7, 8. This final closing movement between contacts 7, 8 will effectively short out the shunting circuit extending around contacts 7, 8 by way of contact arm 99 and contacts 36, 37 disposed interiorly within arc-extinguishing interrupting device 6. Because of the lower resistance between contacts 7, 8 practically all of the load current carried by the switch 4 will pass between the contacts 7, 8, and not through the shunting circuit extending through the interrupting device 6 and the auxiliary contact arm 99.

As mentioned previously, I desire to make the arcextinguishing interrupting device 6 gas-tight to prevent any leakage of the gas, such as sulfur hexafiuoride, existing under some pressure, say one or two atmospheres absolute, within the casing 19. However, to efiect actuation of the mechanism 46 from a point exteriorly of the extinguishing device 6, it is necessary to prevent leakage of gas along the crankshaft 63. An important feature of my invention is the means for preventing such leakage of gas along the crankshaft 68, and this includes a sleeve 193 of rubber, or synthetic rubber, clamped to the crankshaft 68 at the point 109 by a U-shaped clamp 110, the legs of which may be forced together by a bolt 111. To prevent any frictional forces coming into play, preferably the external surface of the crankshaft 68, beneath the sleeve 108, is coated with a dry lubricant, such as graphite. Also the lower end of the sleeve 108, as viewed in Fig. 4, is secured by a clamp 112 to a flange portion 113 forming an integral part of closure plate 87. Another clamping bolt 111 may be employed to secure the two legs of the U-shaped clamp 112 into firm engagement.

With this construction, it will be observed that should there occur any leakage of sulfur hexafluoride gas along the crankshaft 68 past the bearing portion 83, this gas will merely collect in the region 114 within housing 85, and will not be able to escape either past the flange portion 113 or axially along the crankshaft 68. Moreover, any pressure existing within the region 114 will not tend to deform the sleeve 108 of resilient material inasmuch as any compression of the latter will be resisted by the crankshaft 68 itself.

Thus there has been disclosed a gas-tight or liquidtight seal 108, which will permit rotation of the shaft 68 through an arc of about 120, which is the maximum usually required in circuit interrupter mechanisms. It brings about a tight seal and yet offers little resistance to shaft rotation. Further, relatively large pressures can be held without leakage, loss or harm to the seal because movement of the elastic tube walls is limited by the shaft which it surrounds and seals.

Referring to Figs. 5 and 6 of the drawings, it will be observed that I show a modified type of load-break disconnecting switch, generally designated by the reference character 115, including a pair of stationary columns 116, 117 mounted upon a suitable base 118. The upper end of insulator column 116 supports a hinge contact 119 and a disconnecting switch blade 120, pivotally mounted, as at 119a, to the hinge contact 119. Aline terminal 121 is formed by an extension of hinge contact 119.

Suitable means, such as a manually operated hookstick engaging a hook-eye 120a, may be provided to cause engagement of the free contacting end 122 of switch blade 120 with a jaw contact 123, the latter being supported at the upper end of insulator column 117.

Associated with the jaw contact 123 is a pivotally mounted rotatable arc-extinguishing device, generally designated by the reference numeral 124, and including a plurality of conducting metal balls 125 disposed interiorly within an insulating tube 126, such as fiber. The insulating tube 126 is, in turn, surrounded by a weatherproof casing 127 formed of a suitable ceramic weatherproof material, such as porcelain. A closure cap 128 is provided at the right-hand end of the extinguishing device 124, and the cap 128 has a tongue extension 129, which is pivotally supported at 130 on a hinge contact 131. The hinge contact 131 is mounted upon a horizontally extending conducting plate 132, which is, in turn, supported at the upper end of the insulator column 117.

At the left-hand end of the extinguishing device 124 is a second closure cap, generally designated by the reference numeral 133, and having integrally formed actuating portions 134, 135.

In the closed circuit position of the load-break disconnecting device 115, as viewed in Fig. 5, the electrical circuit therethrough includes line terminal 121, hinge contact 119, disconnecting switch blade 120, jaw contact 123 and conducting plate 132 to the second line terminal 136, which preferably constitutes an extension of the conducting plate 132.

To effect opening of the load-break disconnecting switch suitable means, not shown, effects counterclockwise rotative motion of switch blade 120, as viewed in Fig. 5. This causes contacting engagement between the free end 122 of switch blade and the actuating portion 134 of closure cap 133. Such engagement between free end 122 of switch blade 120 and actuating portion 134 causes clockwise rotative movement of arcextinguishing device 124 about the pivot 130. Meanwhile the conducting balls maintain contact between the closure caps 12%, 133. Finally, the contact end 122 of switch blade 1% separates from jaw contact 123 so that the circuit now extends through the extinguishing device 124 by way of the conducting actuating portion 134, closure cap 133, conducting balls 125 to line termi nal 136 by way of hinge contact 131.

Further upward swinging movement of switch blade 1 20 effects rolling motion of all the balls 125 toward the pivoted end of the extinguishing device 124,as shown more clearly in Fig. 6. The circuit is, consequently, broken within the region 137 interiorly within insulating tube 126, which preferably contains a suitable arc-extinguishing gas, such as sulfur hexafiuoride. Further opening movement of switch blade 120 brings the latter to the open circuit position, as shown in Fig. 6.

To effect closing of the disconnecting switch 115, the switch blade 126 is rotated in a clockwise direction, as viewed in Figs. 5 and 6. It finally makes contact with the actuating portion 135, and, in striking the extinguishing device 124, the balls 125 are thrown into a bridging relationship between closure caps 128, 133 so that the circuit is made during the closing operation within the extinguishing device 124, and not at the stationary jaw contact 123.

Further movement effects contact engagement between the free end 122 of switch blade 120 and jaw contact 123 to thereby short out the extinguishing device 124 because of the lower resistance between the contacts 122, 123.

In certain instances, it may be desirable to effect contact closure between the contacts 122, 123 and not through the extinguishing device 124. In such an event a modified extinguishing device, generally designated by the reference numeral 138, is provided, as pictured in Fig. 7. In the modified extinguishing device 138, the actuating portion 135a is formed of insulating material, so that during the closing stroke the striking of the contacting end 122 of switch blade 120 with actuating portion 135a will not complete the circuit through the extinguishing device 138. The circuit will only be closed by actual engagement between contacts 122, 123. Otherwise the extinguishing device 138 is identical with the extinguishing device 124, previously described; consequently a further description of the operation thereof appears unnecessary.

From the foregoing, it will be apparent that I have provided an improved load-break disconnecting switch in which the electrical circuit is interrupted through an auxiliary arc-extinguishing interrupting device and not at the disconnecting switch blade contacts. Thus the switch blade contacts are maintained free from pitting and erosion and are capable of good contacting engagement in the closed circuit position of the device, in which position the extinguishing unit is shorted out of the circuit. The devices are simple and economical to make and will give long operational life.

Although a certain gas has been suggested for use in the extinguishing device 32 of Figs. 14 and the extinguishing devices 124, 138 of Figs. 5 nevertheless other extinguishing gases may well be employed. I have moreover shown an arrangement for providing a gas-tight seal preventing escape of the gas lengthwise of an operating shaft, and I have shown how the mechanism and the contact structure may be opened and closed with a snap action preferably employing a suitable piston for facilitating extinction of the are by means of a blast of compressed gas.

Although I have shown and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art, without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A switching device including a sealed gas-tight casing, an arc-extinguishing gas under pressure within said casing, separable contacts disposed within said gas-tight casing, at least one of which is movable away from the other contact to establish an arc, an. operating shaft, an actuating arm having one end thereof secured to and rotatable with said operating shaft, a second actuating arm having one end thereof pivotally mounted adjacent said operating shaft, an over-center tension spring connected between the free ends of said actuating arms, means connecting said one movable contact to said second actuating arm, and the rotation of said operating shaft causing over-center motion of said over-center spring to cause thereby snap opening motion of said one movable contact to rapidly establish arcing.

2. A switching device including a sealed gas-tight casing, an arc-extinguishing gas under pressure within said casing, separable contacts disposed within said gas-tight casing, at least one of which is movable away from the other contact to establish an are, an operating shaft, an actuating arm having one end thereof secured to and rotatable with said operating shaft, a second actuating arm having one end thereof pivotally mounted adjacent said operating shaft, an over-center tension spring connected between the free ends of said actuating arms, means connecting said one movable contact to said second actuating arm, the rotation of said operating shaft causing overcenter motion of said over-center spring to cause therebysnap opening motion of said one movable contact to rapidly establish arcing, and one end of said operating shaft extending through a wall of said gas-tight casing.

3. A switching device including a gas-tight insulating cylinder having a sealed gas-tight mechanism housing at one end thereof, a pair of separable contacts disposed within said gas-tight insulating cylinder, at least one of which is movable longitudinally of the axis of said insulating cylinder away from the other contact to establish an are, an operating shaft extending through the wall of said mechanism housing, a flexible sealing sleeve member having a gas-tight connection to said shaft and to the mechanism housing, said sleeve member being disposed interiorly of said mechanism housing so that gas pressure forces the sleeve member toward the operating shaft re ceiving support thereby, an actuating arm having one end thereof secured to and rotatable with said operating shaft, a second actuating arm having one end thereof pivotally mounted adjacent said operating shaft, an over-center tension spring connected between the free ends of said actuating arms, means connecting said movable contact to said second actuating arm, and the rotation of said operating shaft causing over-center motion of said over-center spring to cause thereby snap motion of said movable contact.

4. An arc-extinguishing interrupting device including contact structure separable to establish an arc, said device including a gas-tight enclosure housing said contact structure, a mechanism for operating the contact structure including a rotatable shaft extending externally of the gas-tight enclosure, a rubber-like sleeve of considerable length encircling the shaft and having one end clamped thereto, and the other end of the sleeve being clamped to a portion of the enclosure to prevent gas leakage axially along the shaft, and said rubber-like sleeve of considerable length accommodating twisting of the shaft through an arc of about 5. A switching device including contact structure separable to establish an are, said device including a gastight enclosure housing said contact structure, an arcextinguishing gas under pressure in said enclosure, a mechanism for operating the contact structure including a rotatable shaft extending externally of the gas tight enclosure, said shaft being rotatable about its longitudinal axis to actuate the contact structure, a rubber-like sleeve encircling the shaft interiorly of said enclosure housing and having one end clamped thereto, and the other end of the sleeve being clamped to a portion of the enclosure to prevent gas leakage axially along the shaft.

6. A switching device including contact structure separable to an open circuit position, said device including a gas-tight enclosure housing said contact structure, a gas under pressure in said enclosure, a mechanism for openating the contact structure including a rotatable shaft ex-.

tending externally of the gas-tight enclosure, said shaft,

being rotatable about its longitudinal axis to actuate the contact structure, a generally cylindrical flexible sleeve surrounding said shaft inside of the gas-tight enclosure, said flexible sleeve having one end secured to the shaft inside the gas-tight enclosure end having its other end secured to the gas-tight enclosure at the inside thereof, and the gas pressure inside of the gas-tight enclosure acting on the outside of the flexible sleeve, and the shaft inside the sleeve having portions thereon limiting the deformation of the flexible sleeve due to the gas pressure outside thereof.

7. A switching device including a gas-tight insulating cylinder having a sealed gas-tight mechanism housing at one end thereof, a pair of separable contacts disposed within said gas-tight insulating cylinder, at least one of which is movable longitudinally of the axis of said insulating cylinder away from the other contact to establish an arc, an operating shaft extending through the wall of said mechanism housing, an actuating arm disposed Within said mechanism housing having one end thereof secured to and rotatable with said operating shaft, a second actuating arm disposed Within said mechanism housing having one end thereof pivotally mounted around said operating shaft, an over-center tension spring connected between the free ends of said actuating arms, means connecting said one movable contact to said second actuating arm, and the rotation of said operating shaft causing overcenter motion of said over-center spring to cause thereby snap opening motion of said one movable contact to rapidly establish arcing.

8. The combination in a switching device of a sealed gas-tight casing, arc-extinguishing gas under pressure Within said sealed gas-tight casing, a relatively stationary contact, a relatively movable contact movable longitudinally of said casing and carrying a piston thereon, said piston having a movable orifice associated therewith, and opening movement of said movable contact carrying said piston and orifice therewith to force gas through the orifice and adjacent the established arc.

9. The combination in a switching device of a sealed gas-tight casing, an arc-extinguishing gas under pressure within said sealed gas-tight casing, an operating cylinder disposed within said sealed casing, a relatively stationary contact, a relatively movable contact movable longitudinally of said casing and carrying a piston thereon movable within said operating cylinder, said piston having a movable orifice associated therewith, and opening movement of said movable contact carrying said piston and orifice therewith to force gas through the orifice and adjacent the established arc.

10. The combination in a switching device of a sealed gas-tight casing, an arc-extinguishing gas under pressure Within said sealed gas-tight casing, a relatively stationary contact positioned within said casing adjacent one end thereof, an arc-extinguishing cylinder within said casing composed of insulating material and mounted at one end thereof adjacent said relatively stationary contact, a relatively movable contact movable longitudinally of said casing and carrying a piston thereon movable within said arc-extinguishing cylinder, said piston having a movable orifice associated therewith, and opening movement of said movable contact carrying said piston and orifice therewith to force gas through the orifice and adjacent the established arc.

11. The combination in a switching device of a sealed gas-tight casing, an arc-extinguishing gas under pressure within said sealed gas-tight casing, a relatively stationary contact positioned within said casing adjacent one end thereof, an arc-extinguishing cylinder within said casing composed of insulating material and mounted at one end thereof adjacent said relatively stationary contact, the other end of said arc-extinguishing cylinder being closed, a relatively movable contact movable through the closed end of said arc-extinguishing cylinder longitudinally of said casing and carrying a piston thereon, said piston 12 being movable within said'arc-extinguishing cylinder, said piston having a movable orifice associated therewith, and opening movement of said movable contact carrying said piston and orifice therewith to force gas through the orifice and adjacent the established are.

12. A high voltage switching device including contact structure separable'to an open position, said device including a gas-tight enclosure housing said contact structure, a gas under pressure in said enclosure, said enclosure including a tubular member of insulating material and a metallic closure member at high potential sealed to one end thereof, upstanding insulating means for supporting said closure member at high potential a safe distance above ground potential, and a pressure indicating device facing the ground and connected through said closure member sealed to the end of the tubular member of insulating material responsive to the pressure of the gas in the enclosure.

13. A high voltage switching device including a vertically mounted column of insulating material, contact means separable in said vertically mounted column of insulating material, gas under pressure in said vertically mounted column of insulating material, a conducting closure member at high potential sealed to the lower end of said vertically mounted column of insulating material, upstanding insulating means for supporting said closure member at high potential a safe distance above ground potential, and a pressure responsive device facing downwardly and connected through said closure member at said lower end to be responsive to the pressure of the gas in the enclosure.

14. A high voltage switching device including an upstanding column of insulating material, conducting closure means at high potential for the upper and lower ends of said column of insulating material, gas under pressure in said column of insulating material, contact means separable in said gas under pressure, upstanding insulating means for supponting said conducting closure means at high potential a safe distance above ground potential, a gas pressure indicator connected through the closure means for the lower end of the upstanding column of insulating material to be responsive to the pressure of the gas therein, and said gas pressure indicator facing downwardly so that its indication is visible from below the lower end of the column.

15. A high voltage switching device including an up standing column of insulating material, conducting closure means at high potential for the upper and lower ends of said column of insulating material, gas under pressure in said column of insulating material, contact means separable in said gas under pressure, a movable member for operating said contact means extending through one of said closure means and having a pressure retaining seal therewith, a gas pressure indicator connected through the closure means for the lower end of the upstanding column of insulating material to be responsive to the pressure of the gas therein, structural insulating means beneath the high potential closure means for the lower end of the upstanding column of insulating material to support the same a safe distance above ground potential, and said gas pressure indicator being positioned beneath said structural means and facing downwardly so that its indication is visible from ground potential below the said structural means.

References Cited in the file of this patent UNITED STATES PATENTS 882,340 Palmer Mar. 17, 1908 1,336,069 Conrad Apr. 6, 1920 1,458,090 Waldron June 5, 1923 1,522,498 Conrad Jan. 13, 1925 1,706,746 Rice Mar. 26, 1929 (Other references on following page) UNITED STATES PATENTS 2,598,446 Schneider May 27, 1952 1 70 ,7 2 i i d Man 2 1929 2,629,791 Le Tourneau 1953 1,91 ,717 De Giers July 4, 1933 ,7 L g l 6t y 1956 2,023,486 McComb' Dec. 10, 1935 2,281,385 Saint Germain et a1 Apr. 28, 1942 5 FOREIGN PATENTS 2,462,753 Kyle et a1. Feb. 22, 1949 553,665 Great Britain May 31, 1943 2,551,772 Thibaudat May 8, 1951 272,499 Great Britain Nov. 10, 1927 

